Splash Digital orthodontics Peter Søndergaard, 3Shape A/S

What is orthodontics (problems, brackets, aligners) Traditional orho (gypsum scans, direct bonding, ) Digital ortho (scanning, aligners by moving teeth) Simple vs realistic aligner construction Osteoclas

Orthodontics: Definition The first specialty created in the field of dentistry The area is concerned with the diagnosis, prevention and correction of mal-positioned teeth and/or jaws Derived from the Greek words orthos ("correct", "straight") and dontia ("teeth")

When do Patients typically need an Orthodontist? Functional Problems (e.g. problems chewing the food properly) Esthetic Problems (of all kinds) Problems with the Temporomandibular Joint (TMJ)

Esthetic Problems: Examples Missing teeth Crowding Unwanted profile Spacing

Tooth Movements Crown tipping Root tipping Torquing Rotation Translation Extrusion Intrusion

How does tooth movement work?

What kind of Treatments do an Orthodontist offer? Metal Braces Ceramic Braces Removable Braces Functional Appliances Aligners Lingual Braces Retainers Mouth Guards And more !

How Braces work

How Braces work Fundamental idea: The arch wire will return to its original shape, and apply enough force to move the tooth. 1 N of force can move a tooth sideways

How Aligners Work Takes you from the current situation (malocclusion) – to the ideal setup (straight teeth) Typically involve 20-40 (slightly different) aligners in a set – which you exchange with an interval dictated by the doctor Treatment typically takes between 12-24 months

Simple digital workflow for making aligners Step 1: Scan Step 2: Segment Step 3: Model individual teeth Step 4 : Move teeth models YouTube Virtual Setup Step 5: Export to STL Step 6: Print and press

Problems arise Aligners are made of plastic, not metal, so they apply less force The contact points of the aligner are not as well defined as for brackets Results: Aligners treatments made using this method are sometimes ineffective

Solution The problem is that the aligner is designed based on where we want the tooth to move We should instead design the aligner to produce the force necessary to move the tooth to the correct position For this, we need to know the correct force field to obtain a desired position Solve the simpler problem first: Given a force field, how does the teeth move?

Modeling tooth movements Tooth movements depends on: Force vector applied Area of bone/periodontal ligament Thickness of bone around the tooth Bone age of the patient (does s/he grow new bone) Collisions of the crowns Collisions of the roots ...

Which data does an orhodontist make his decision? Physical impression of the patient Medical history, also of the family Facial photos X-ray´s: Sideways Panoramic CBCT (hard cases) Intraoral scan

What data do we have to work with? Surface scans Panoramic 2D x-ray

CBCT CBCT (Cone-beam computed tomography): 3D volumetric